Plasma-arc torch with gas cooled blow-out electrode

Claim 1

A plasma-arc cutting torch comprising: a torch housing defining a chamber having an outlet at the end of said chamber; gas supply means for supplying a gas to said chamber, said gas being suitable for generating plasma and for a secondary gas flow which will cool the torch and a workpiece; an electrode in the chamber adjacent to the outlet, said electrode being generally elongated and defining a central axis and having first and second opposite ends. attachment means on said first end of said electrode for removably mounting said electrode within said chamber in said torch housing, an insert bore in said second end extending into said electrode, an insert fitted within and closing off said insert bore, gas separation means in said chamber for separating said gas into a primary gas flow adjacent to said electrode for generating a plasma and a secondary gas flow away from said electrode for cooling the torch and the workpiece, wherein said gas separation means comprises, a generally cylindrical, electrical insulator at least partially surrounding said electrode, said insulator defining an outer chamber with said body and further including passage means for directing gas from said gas supply means to said outer chamber, a cup-shaped torch tip around the end of said electrode and closing off said outlet except for an opening in said tip, said tip and said insulator defining, with said insulator, an inner chamber around said electrode, passage means in said insulator for directing primary gas flow from said gas supply means to said outer chamber, and thence to said inner chamber, and wherein said passage means comprises tangentially directed passages in said insulator so that primary gas from said gas supply means will generate a vortex around said electrode.